The JSTL Core <c:catch> tag is used in exception handling to handle errors that occur during runtime by catching any Throwable object(an exception) in its body.
Attributes of <c:catch> Tag
The <c:catch> tag has a single optional attribute:
- var: The name of the page-scoped variable to store the exception in. If this attribute is not specified, the exception will not be stored in any variable.
Example of <c:catch> Tag
The following example shows how to use the <c:catch> tag to detect an arithmetic error of divide-by-zero as an exception:
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> <html>
<head>
<title>JSTL Core <c:catch> Tag Example</title>
</head>
<body>
<c:catch var="catchtheException">
<% int x = 2 / 0; %>
</c:catch>
<c:if test="${catchtheException != null}">
<p>An exception occurred: ${catchtheException.message}</p>
</c:if>
</body>
</html>
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In this code, we divide a number by zero, which is not possible in mathematics thus resulting in an error. The <c:catch> tag will catch this exception and store it in the variable catch the exception. The <c:if> tag will then check if the variable is null. If it is not null, then the exception message will be displayed to the user.
Note: Since division by zero(0) is not possible in Mathematics, it can be thrown as error.
Usage of <c:catch> Tag
There can be many use cases for <c:catch> tag. Some of them are listed below:
- Can also be used in log generation into a file/database.
- You can also use this tag to detect an error and redirect the user to an error page.
- It can also be used to provide the user with an option to retry.
The <c:catch> tag is overall a great tool for handling exceptions in JSP pages. It can help you to create more robust and user-friendly applications.